APIM failures seemed to be a bigger problem back when I bought my 2018. Had many gremlins with the electrical system, changed the APIM twice along with the battery and all was good. Had no problems with the 2021 and the 2023 has been great.
Try LAs Awesome, Home Depot or the other big box stores sell it. I use to to remove dried sap and dirt from my F350 plow truck that sits in the woods. Nothing else was so easy, spray it on and wipe it off, should take care of your problem...
I have had problems with that system on my 21 and 23. Works when it wants, then wont work for months. I gave up on it as just another crappy idea that doesnt work.
Had the Jayco version with the toy hauler deck for several years and loved it. Quick easy setup, travel at 75 mph and tucked into the pole barn to keep it nice and clean.